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Chapter Measurement

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**Measurement Is a determination of the amount of something**

Is defined as a comparison to a known standard What does “5 feet tall” mean???? Do you have to know what a foot is in order for this to make sense? Measurements have two parts, a number value and a unit

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**Units and Standards What is a standard ?**

1.) Historically things such as hands and feet were used to make measurements, and other things were compared to that size. 2.) A standard is something that you compare other amounts to.

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**Two Measurement Systems**

English system-used for everyday measurement in the US. Include units of miles, feet, inches, pounds, pints, quarts, gallons, cups, and teaspoons Metric System

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Measurement In 1960 an International Committee agreed to a system of standards to be used by scientists worldwide. Scientists use the metric system or SI for le System Internationale d’Units Makes sharing data easier Goal for using metric system was to have all units of measurement be related

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**Metric System Units include a Base unit and prefix**

Base units include Liters, meters, and grams Prefixes multiply or divide the base units by multiples 10

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**Prefixes Prefix Symbol Meaning As a number kilo- k thousand 1,000**

mega- M million 1,000,000 giga- G billion 1,000,000,000 deci- d tenth 0.1 centi- c hundredth 0.01 milli- m thousandth 0.001 micro- m millionth

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**Conversion factors…. 1000 milli-units = 1 base unit**

100 centi-units = 1 base unit 10 deci- units = 1 base unit 1000 base units = 1 kilo-unit

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**1. 2 Time and Distance Time is used in two ways**

To indicate a particular moment in the past or the future Tomorrow at 3:00 To indicate a quantity of time…. 30 seconds minutes, 15 seconds

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**Measuring Length/Distance**

Use a ruler/taper measure Line up from zero not the end of the ruler Small divisions are millimeters

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Vernier Caliper Micrometer This reads 3.3

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Mass Weight is the force of gravity acting on an object, mass is the amount of matter in an object. (they are different things) Metric unit of mass is the gram 1gram is defined as the mass of 1 cm3 of water at 4 ºC. 1 kg = 1 L of water 1 kg = 2.2 lbs 1 g = 1 small paper clip 1 mg = 10 grains of salt or 2 drops of water.

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**Measuring Mass Use a triple beam balance First balance it at zero.**

Then put item on Then move one weight at a time When balanced, add up the weights

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**Volume Defined as the space occupied by some object or substance**

Liter a common unit, cubic meter (m3) is SI unit 1 L about 1/4 of a gallon - a quart 1 mL is about 20 drops of water or 1 sugar cube 1 ml = 1 cm3

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**Measuring Volume of a Liquid**

Use a graduated cylinder. The water will curve in the cylinder. Hold it level with your eye. Read the bottom of the curve (meniscus) Measures in milliliters mL.

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**Measuring Volume of a solid Object**

Can be accomplished by using the “displacement method” Objects in water will displace, or push aside, their volume in water. 1. Record initial volume 2. Record Final Volume 3. Subtract initial volume from final volume to get volume of object

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**Measuring Volume of Regular Solid Object**

You can calculate the volume of a regular object such as a cube or rectangular solid by using the equation Volume = Length X Width X Height Volume calculator

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**Density Density = Mass Volume**

Description of matter that is a comparison of mass and volume Calculated using the equation Density = Mass Volume Density of water = 1 g/cm3 = 1000kg/m3 If material density > water, it will sink If material density < water, it will float

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**Temperature Measured with a thermometer**

Common metric units are either Celsius or Kelvin Measure of the average kinetic energy of molecules or atoms of a substance (faster ones have more KE and are “hotter”) Water freezes at 0°C, boils at 100°C

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**Temperature Conversions**

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Time Common base unit of seconds, but can be measured in hours/days/years/etc.. 1 year = 365 days 1 day = 24 hours 1 hour = 60 minutes 1 minute = 60 seconds

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Force Use a force gauge to measure, or a spring scale like we use in this class Measure in units of “Newtons”

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**Metric conversions Changing the unit**

Does not change the size of the measurement If the unit gets bigger the number gets smaller If the unit gets smaller the number gets bigger Math with multiples of 10 We will cancel out units to make sure we set the problem up right

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Metric conversions “A common race is the 5 K, which is 5 km. How many meters is this?” Given unit -km Unit wanted –m The unit gets smaller, so the number must get bigger 1000 m = 1 km

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**Metric conversions 1000 m Distance in m = 5 km x 1 km**

Distance in m = 5000 m

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Metric conversions The recommended daily requirement of vitamin C is 500 mg. How many grams is this? 1 g mass in g = 500 mg x 1000 mg mass in g = 0.5 g

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**How many centimeters are there in 5.7 meters?**

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**100 kilometers/hour is a typical speed limit in Canada**

100 kilometers/hour is a typical speed limit in Canada. What is this speed equal to in meters/sec?

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